Claudio Naranjo was a Chilean psychiatrist. He was co-developer of the Enneagram of Personality. His studies and investigations oftenly focused in the search of spirituality to find mental stability, and also some times, the use of lisergic substance to free hidden and harmful thoughts.
The second chapter of Naranjo's somewhat esoteric treatment of meditation lays out intriguing schemas of the space of all possible meditative practices. On the whole, I found the book hard to get through, reaching only the arcane chapter on body awareness. But I would like to finish reading it at some point.